modulation code

例句：

1. 1. The modulation code is used to control the frequency of the radio signal.
   调制码用于控制无线电信号的频率。
2. 2. The modulation code was designed to improve the quality of the audio signal.
   调制码被设计用来提高音频信号的质量。
3. 3. The modulation code is essential for transmitting data over long distances.
   调制码对于在长距离上传输数据至关重要。